A catalyst complex for catalysis of degradation of a polymer material is described. The complex comprises a magnetic particulate body containing iron oxide at its surface with an average diameter of 150-450 nm, and a plurality of catalytic groups grafted onto the iron oxide surface of the magnetic particulate body, wherein the catalytic groups comprise a bridging moiety and a catalyst entity, thebridging moiety comprises a functional group for adhesion or bonding to the iron oxide surface and a linking group towards the catalyst entity, and the catalyst entity comprises a positively charged aromatic heterocycle moiety, and a negatively charged moiety for balancing the positively charged aromatic moiety.